How to Read Tendon's Rope Specifications

Tendon ropes not only follow the highest standards of quality and safety, they innovate to create new high standards in the industry.  Every rope undergoes rigorous testing, both in a lab and tested by athletes in a natural environment.  

Let's say you just purchased a brand new Tendon Master Pro 9.7, what testing was done to ensure that your rope was held to the same quality as all the others on the shelf?  Are there standards out there that companies have to follow?  What do all the stats on the rope mean and where do they come from?  In this blog we plan to explain all this to you, so you can make your decision on what climbing rope is best for you.  

When looking at Tendon Ropes, there are two sections of stats to look into, the features on the left hand side, and the stats on the right. 

The featured pictograms on the left show the technology that makes the ropes special.  For example, it could tell you if a rope has a dry treatment, or a middle marker.  This is a quick place to look at and be able to tell if the rope has all the featured technologies you are looking for before you purchase.  It can be an easy way to compare two different models and see what sets them apart.  

On the right, we list all the specifications of the rope.  The specifications shown follow EN892 standards, which we can explain going from top to bottom:

Rope Diameter - For single ropes, this parameter is measuring the diameter of the rope while applying a 10kg load to it.  For half ropes, the diameter is measured with a 6kg weight, and for twin ropes the diameter is measured with 5kg.  The diameter of the rope while the weight is on it is the diameter listed in the specifications. 

Most climbers you run into like their rope diameter to be between 9.4mm to 9.8mm.  In the 1990’s most climbers would have said 10.2mm was the best diameter for a rope.  When I first started climbing in 2012, 9.8mm was considered the best diameter by most climbers.  Now, 9.2mm-9.6mm is getting more common to see.  Over time the ‘golden range’ for rope diameter has changed as technology has improved the quality of climbing ropes.  Climbers look for a combination of lightweight (small diameter) and durability, and their favorite size rope will depend on whether they value weight or durability more.  (tip: If you are competing for USA Climbing, the rope diameter needs to be at least 9.5mm)

Weight - as expected, this is the weight of the rope.  Tendon lists their ropes in grams per meter.  There is approximately 453.6 grams in one pound, so using the Tendon Master Pro 9.7 for an example (65g/m), the rope would be 0.142 lbs per meter, or about 8.6lbs for a 60 meter rope.  

If you are primarily climbing inside a gym, weight does not matter much to you.  However if you are hiking on long approaches to your local crags, then a couple pounds off your pack can make a big difference! 

Number of UIAA Falls - This is the minimum number of factor two falls that the rope can withstand during a test.  A UIAA test fall recreates the conditions of a factor two fall using an 80kg weight (approx. 176.4 pounds).  This may not seem like much weight until you understand what exactly a factor two fall is.  A factor two fall in rock climbing refers to a specific type of fall where the distance fallen is twice the length of the rope between the climber and their last point of protection.  For example, if you are climbing 20 feet above a bolt, and you were to fall to 20 feet below your last anchor, then you would have a factor two fall.

Maximum Impact Force - The maximum impact force is a crucial parameter measured during UIAA (International Climbing and Mountaineering Federation) rock climbing rope testing. It represents the peak force experienced by the climber and the rope system during a simulated fall. The UIAA sets standards and conducts testing to ensure that climbing ropes meet certain safety criteria.

During testing, a weight is dropped onto a secured rope to simulate a fall. The maximum impact force is the highest force recorded during this fall arrest process. It is measured in kilonewtons (kN). The goal is to ensure that the rope and the entire climbing system can absorb and dissipate enough energy to reduce the force exerted on the climber and the protection (such as anchors and gear) to acceptable levels.

Lower maximum impact forces are generally preferred, as they indicate that the climbing rope is able to stretch and absorb more energy during a fall. This elasticity helps reduce the impact on the climber, the gear, and the overall system, thereby enhancing safety. Climbing ropes meeting UIAA standards provide a balance between strength, dynamic elongation, and the ability to absorb energy to minimize the impact forces on the climber and the climbing system.

Static Elongation -  In climbing, static elongation refers to the amount a rope stretches when a steady, non-dynamic force is applied, as opposed to dynamic elongation, which is the stretch that occurs during a sudden, dynamic load like a fall. During static elongation testing, an 80kg (176.4 lb) weight is applied to the rope, and the amount of stretch is measured. The result is usually expressed as a percentage of the rope's original length. For example, if a 60-meter rope stretches 6 meters when the weight is attached to it, then it would have a 10% static elongation.  For EN892 and UIAA regulation, a dynamic rock climbing rope should not have a static elongation that exceeds 10%.

Dynamic Elongation - In the dynamic elongation test, a weight is dropped onto a secured rope to simulate a factor two dynamic fall. The test quantifies the maximum stretch of the rope during this dynamic loading. Results are typically expressed as a percentage of the rope's original length. For instance, if a 60-meter rope extends an additional 20 meters during the factor two test fall, the dynamic elongation would be 30%. UIAA standards dictate a maximum dynamic elongation of 40%.

Climbing ropes with higher dynamic elongation values can better absorb energy in a fall, leading to reduced impact forces on the climber and the protection system. This elasticity is advantageous in climbing scenarios as it helps diminish the peak force transmitted to the climber and anchor points, thereby enhancing safety.

Sheath Slippage - In the majority of ropes, the sheath and core are not fused together. The sheath slippage test involves taking a slightly over 2-meter sample of rope and subjecting it to simulated loading through a specialized apparatus. This test measures the displacement or movement of the sheath relative to the core, and if there is significant slippage, it can compromise the safety and integrity of the rope.

Following the test, sheath slippage can be either a positive or negative value. A positive value means the sheath became longer than the core, while a negative value indicates the core became longer than the sheath when loaded. According to EN 892 standards, the allowable sheath slippage is up to 2% (40 mm of the sample), and the UIAA standard is even stricter, permitting a maximum of 1% (20 mm of the sample). These standards ensure that climbing ropes meet specific criteria for safety and performance by limiting sheath slippage to acceptable levels.

Knotability - The ability to tie knots is paramount in rock climbing.  The knotability of a rope can be influenced by a number of factors, including the rope’s flexibility, texture of the sheath, construction of the rope, and the diameter of the rope.  

In the knotability test, a simple overhand knot is tied and then a 10kg weight (approx 22 lbs) is applied to the end of the rope.  The weight at the end of the rope will slightly tighten the knot, and the inside diameter of the gap inside the knot is measured, and the knotability will be a ratio of the size of the gap compared to the diameter of the rope.  UIAA standards dictate that ratio shall not exceed 1.1 times the rope diameter.